Recently, next generation display devices are being actively developed, and EL display devices that have a first electrode, a plurality of organic layers including a light-emitting layer, and a second electrode layered in order on a driving substrate are attracting attention. EL display devices have features such as self-generated light emission and therefore a wide viewing angle, no backlight requirement and therefore low power consumption, high responsiveness, and properties that enable reduced device thickness. Thus, application of EL display devices to large screen display devices such as televisions is strongly desired.
For color displays, red, blue, and green three-color pixel displays are most typical, but with the aims of improved power saving and reliability, red, blue, green, and white four-color pixel displays and red, blue, green, and pale blue four-color pixel displays are being developed by various companies.
In an organic EL light-emitting element it is necessary to form an organic EL light emitter for each pixel, such as a red, blue, and green three-color organic EL light emitter or a red, blue, green, and white four-color organic EL light emitter.
The most typical manufacturing process for manufacturing individual organic EL units is by using vapor deposition into minute holes in a fine metal mask. For example, an organic EL unit emitting red light is formed by vapor deposition using a fine metal mask for red, an organic EL unit emitting green light is formed by vapor deposition using a fine metal mask for green, and an organic EL unit emitting blue light is formed by vapor deposition using a fine metal mask for blue, thereby forming a red, green, and blue light-emitter.
However, to form large organic EL light-emitting elements and reduce costs, development of organic EL light-emitting element technology using large substrates is of importance.
Recently, two methods of forming organic EL light-emitting elements using large substrates are attracting attention.
A first method is a method of forming white organic EL elements in all display areas and achieving a color display by using a red, green, blue, and white four-color color filter. This method is effective in forming large screens and high-definition displays.
Another method is a coating method of forming organic EL light emitters. As coating methods, various manufacturing methods have been considered. They can be roughly classified into: methods using relief printing, flexographic printing, screen printing, gravure printing, etc.; and methods using inkjet printing (see Patent Literature 1).